Abstract Posttraumatic stress disorder (PTSD) is prevalent among combat veterans and is a substantial public health burden. Several psychotherapies, including cognitive processing therapy (CPT) and prolonged exposure (PE) therapy, have been recommended as efficacious for the treatment of PTSD and are being disseminated nationally in the VA Healthcare System. Yet many individuals show limited benefit from such treatments. Accumulating evidence, including from our group, indicates that episodic memory deficits may be one factor limiting psychotherapy treatment efficacy in PTSD. However, cognitive functioning is not often considered during PTSD treatment, and Veterans with cognitive impairment may therefore be receiving treatments that are suboptimal. Thus, systematic studies of how cognitive dysfunction impacts treatment response are greatly needed to identify relevant, potentially modifiable factors affecting psychotherapy outcomes and inform the development of effective rehabilitation interventions for individuals with PTSD. Critically, no studies to date have examined the pathways by which cognitive functioning may affect treatment and functional outcomes. To address this limitation, the proposed project aims to test specific models of pathways between memory dysfunction and therapeutic and functional outcomes by integrating novel insights from both cognitive neuropsychology and psychotherapy research. Approximately 140 Veterans with PTSD will be enrolled at the Corporal Michael J. Crescenz Philadelphia VA Medical Center (CMC VAMC) and CMC VAMC Community- Based Outpatient Clinics (CBOCs). All participants will undergo a standard, 12-session course of CPT by certified and experienced study therapists. Participants will undergo assessments at baseline, mid-treatment, and end of treatment. At baseline, participants will receive diagnostic interviews, behavioral questionnaires, and a comprehensive cognitive assessment, including measures of executive control, emotion processing, verbal functioning, emotionally-neutral episodic memory, and autobiographical memory. Assessments of PTSD symptoms, treatment engagement, memory for treatment content, and functional outcomes will be collected longitudinally. The proposed study will determine whether verbal memory is a specific predictor of CPT outcomes in PTSD, including both symptom reductions and functional outcomes (Aim 1). The study will also determine the pathways by which memory functioning affects treatment outcomes by examining relationships between memory functioning, treatment engagement, recall of treatment content, and illness course. More specifically, analyses will examine whether memory for treatment content mediates the relationship between memory functioning and treatment outcomes (Aim 2). Finally, exploratory analyses will examine whether alternative models of memory dysfunction in PTSD (e.g., autobiographical memory) provide increased prediction of treatment and functional outcomes relative to verbal memory (Aim 3). Findings from this line of research will provide critical insights into the specific mechanisms underlying psychotherapy treatment response in PTSD and lead to the identification of novel rehabilitation targets (e.g., memory for the content of treatment). As such, this study could have broad clinical implications, as focusing on these treatment targets could enhance outcomes across a range of psychotherapy interventions. For example, ?fine tuned? psychotherapies could be developed to enhance memory for treatment content by providing focused memory support interventions, which could be broadly applied to help facilitate treatment effectiveness.